Encircle the weaker base between the two. Explain why.
HSe⁻ or HS⁻

HSe⁻;

Its corresponding acid (H₂Se) has a longer and weaker bond to H, making it a stronger acid and its conjugate base (HSe⁻) a weaker base.

HS⁻;

Its corresponding acid (H₂S) has a longer and weaker bond to H, making it a stronger acid and its conjugate base (HS⁻) a weaker base.

Neither of the two;

The two conjugate bases are similar in strength since the central atoms belong to the same group.

Neither of the two;

The two conjugate bases are similar in strength since the central atoms have very close radii and electronegativities.